Create fillable PDF form with exams2nops - r-exams

Question

We think about distributing an open-book exam as a fillable PDF form via exams2nops. The idea is that students do not print the PDF and mark their answers with a pen, but rather fill in their answers electronically in their PDF (e.g. with Acrobat Reader), and send back that PDF to us (or upload it via Moodle). Then, the PDF is "scanned" / the answers are extracted from the PDF.
Currently, the checkboxes for MC/SC answers are not clickable; also the textfields for free text answers could be fillable text input fields. The current PDF export does not do this.
Has anybody done this already? If I'd like to implement this, where is a good starting point? Maybe nops.tex?
(We are aware that exporting to an interactive quiz in Moodle is an alternative option).

Answer 1

TL;DR
exams2nops() does not support this and will not be extended in this direction because its focus is generating PDF exams for printing/scanning/etc.
exams2pdf() can be customized to use different LaTeX templates and you can try to set up a suitable template using the {hyperref} package.
The support for the resulting PDF forms differs a lot between PDF viewers, typically with Acrobat Reader being the only one with decent support.
My personal experience with the heterogeneity on students' systems plus sending solutions via e-mail is that this is not a very reliable solution but would be the source of a lot of problems. Personally, I would avoid going down this road.
If your university hosts a Moodle system, I would recommend generating exams via exams2moodle(). At least the responsibility for the stability of the system is then with the university.
Details:
By using the {hyperref} package you can use the {Form} environment with commands like \CheckBox{}, \TextEntry{}, etc. A brief overview is given here: https://tex.stackexchange.com/questions/14842/creating-fillable-pdfs
A more elaborate worked example is available at: https://martin-thoma.com/creating-pdf-forms-with-latex/
Based on these I adapted the exam.tex template provided within the R/exams package and set up a form.tex template. The full LaTeX code is included below. This tries to do the following:
Set up a form that can be submitted by e-mail when completed.
The form consists of "fixed" fields for name and student ID.
Then it sets up commands \exnum, \exstring, exmchoice etc. that can be used by exams2pdf(). See Section 3 in vignette("exams", package = "exams") for details. Thus, these commands are repeated as often as necessary for a given exam.
At the end there are buttons to "Submit" or "Clear" the form.
For illustration, try:
exams2pdf(
c("deriv.Rmd", "swisscapital.Rmd", "boxplots.Rmd", "ttest.Rmd", "function.Rmd", "lm.Rmd"),
template = "form.tex"
)
where form.tex from below needs to be in your current working directory.
The result is a form1.pdf displayed automatically in your default PDF viewer (see options(pdfviewer = ...)). Alternatively, you can also add an argument dir = "." to store the file in your current working directory.
For me on Debian GNU/Linux with TeXLive this works and produces a PDF file that can be viewed and filled in using the Evince PDF viewer. However, neither "Submit" nor "Clear" works.
When I open the same file under Acrobat Reader in Windows 10, then only the TextEntry fields for Name/ID work, the others don't. The check boxes work but all checkboxes for (a) are linked, as are all (b), etc.
My impression is that composing the {Form} on the fly like this does not work for Acrobat Reader. But I would appreciate pointers how this can be fixed. An alternative would be to exactly code the form you need for a specific exam with unique name tags in all form elements etc.
Bonus note:
The template below also activates the {attachfile} LaTeX package which can be used to embed files (e.g., data sets) into the PDF. This works for me but only under Acrobat Reader. To automatically convert all \url{} commands (as created for the lm exercise, used above) into \attachfile{} commands, the development version of exams2pdf() gained an argument attachfile = FALSE which can be set to TRUE. See this thread in the R/exams forum on R-Forge for more details:
https://R-Forge.R-project.org/forum/forum.php?thread_id=32091&forum_id=4377&group_id=1337
LaTeX template: form.tex
\documentclass[10pt,a4paper]{article}
%% packages
\usepackage[utf8]{inputenc}
\usepackage{a4wide,color,verbatim,Sweave,url,xargs,amsmath,booktabs,longtable,eurosym}
%%% %% optionally: two-column layout for exercise form
%%% \usepackage{multicol}
%% embed supplementary data files etc.
\usepackage{attachfile}
\attachfilesetup{color=0.5 0 0}
%% support PDF forms
\usepackage{hyperref}
%% new environments
\newenvironment{question}{\item}{}
\newenvironment{solution}{\comment}{\endcomment}
\newenvironment{answerlist}{\renewcommand{\labelenumi}{(\alph{enumi})}\begin{enumerate}}{\end{enumerate}}
%% paragraphs
\setlength{\parskip}{0.7ex plus0.1ex minus0.1ex}
\setlength{\parindent}{0em}
%% compatibility with pandoc
\providecommand{\tightlist}{\setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}
\setkeys{Gin}{keepaspectratio}
%% fonts: Helvetica
\usepackage{helvet}
\IfFileExists{sfmath.sty}{
\RequirePackage[helvet]{sfmath}
}{}
\renewcommand{\sfdefault}{phv}
\renewcommand{\rmdefault}{phv}
\newcommandx{\exmchoice}[9][2=-,3=-,4=-,5=-,6=-,7=-,8=-,9=-]{%
\CheckBox[name=a, width=1em]{(a)}~~%
\if #2- \else \CheckBox[name=b, width=1em]{(b)}~~ \fi%
\if #3- \else \CheckBox[name=c, width=1em]{(c)}~~ \fi%
\if #4- \else \CheckBox[name=d, width=1em]{(d)}~~ \fi%
\if #5- \else \CheckBox[name=e, width=1em]{(e)}~~ \fi%
\if #6- \else \CheckBox[name=f, width=1em]{(f)}~~ \fi%
\if #7- \else \CheckBox[name=g, width=1em]{(g)}~~ \fi%
\if #8- \else \CheckBox[name=h, width=1em]{(h)}~~ \fi%
\if #9- \else \CheckBox[name=i, width=1em]{(i)}~~ \fi%
}
\newcommandx{\exclozechoice}[9][2=-,3=-,4=-,5=-,6=-,7=-,8=-,9=-]{\setcounter{enumiii}{1}%
\CheckBox[name=ca, width=1em]{\roman{enumiii}.} \stepcounter{enumiii}%
\if #2- \else \CheckBox[name=cb, width=1em]{\roman{enumiii}.} \stepcounter{enumiii} \fi%
\if #3- \else \CheckBox[name=cc, width=1em]{\roman{enumiii}.} \stepcounter{enumiii} \fi%
\if #4- \else \CheckBox[name=cd, width=1em]{\roman{enumiii}.} \stepcounter{enumiii} \fi%
\if #5- \else \CheckBox[name=ce, width=1em]{\roman{enumiii}.} \stepcounter{enumiii} \fi%
\if #6- \else \CheckBox[name=cf, width=1em]{\roman{enumiii}.} \stepcounter{enumiii} \fi%
\if #7- \else \CheckBox[name=cg, width=1em]{\roman{enumiii}.} \stepcounter{enumiii} \fi%
\if #8- \else \CheckBox[name=ch, width=1em]{\roman{enumiii}.} \stepcounter{enumiii} \fi%
\if #9- \else \CheckBox[name=ci, width=1em]{\roman{enumiii}.} \fi%
}
\newcommand{\exnum}[9]{\TextField[name=num, width=4cm]{}}
\newcommand{\exstring}[1]{\TextField[name=string, width=4cm]{}}
%% new commands
\makeatletter
\newcommand{\ID}[1]{\def\#ID{#1}}
\newcommand{\Date}[1]{\def\#Date{#1}}
\ID{00001}
\Date{YYYY-MM-DD}
%% \exinput{header}
\newcommand{\myID}{\#ID}
\newcommand{\myDate}{\#Date}
\makeatother
%% headings
\markboth{\textnormal{\bf \large Statistics Exam: \myID}}%
{\textnormal{\bf \large Statistics Exam: \myID}}
\pagestyle{myheadings}
\begin{document}
%% title page
\thispagestyle{empty}
{\sf
\textbf{\LARGE{R University}}
\textbf{\large{Statistics Exam \myDate \hfill Exam ID \myID}}
\vspace*{2cm}
\begin{Form}[action=mailto:info#example.com,encoding=html,method=post]
\begin{tabular}{ll}
\textbf{Name} & \TextField[name=Name, width=10cm]{}\\
\textbf{Student ID} & \TextField[name=ID, width=10cm]{}\\
\end{tabular}
\vspace*{1cm}
%%% \begin{multicols}{2}
%% \exinput{questionnaire}
%%% \end{multicols}
\Submit{Submit} ~~ \Reset{Clear}
\end{Form}
}
\newpage
\begin{enumerate}
%% \exinput{exercises}
\end{enumerate}
\end{document}

Answer 2

we will structure our exam like this:
students download pdf created with exams2nops
students open pdfs with Adobe Acrobat Reader DC (free: https://get.adobe.com/de/reader/?promoid=P79NQR4R&mv=other) and mark the boxes with X via the "sign" option
students upload the first filled page of the exam back (via print to pdf). The advantage of this is that the set crosses can no longer be changed.
normal evaluation process of exams starts...